Color formation and color stability are amongst the most critical quality traits of processed meat products and thus of great importance to the meat industry. The characteristic cured color can be derived from the concentration of heme pigments (myoglobin, hemoglobin), their chemical states and additives such as nitrogen oxides and reducing agents. In standard fermented meat products, such as salami, the characteristic cured color is a result of the chemical reaction between compounds derived from added nitrite/nitrate and the naturally occurring red myoglobin leading to the simultaneous formation of the bright red nitrosylmyoglobin, in which an axial ligand nitric oxide (NO) is coordinated to the central Fe2+ in heme.
Despite of all its desired properties (color formation, microbiologic safety), the safety of nitrite to human health has been questioned. Nitrite can cause the formation of unwanted compounds in cured meat, like N-nitrosamines which are questionable in regard to health. These compounds can be formed in principle due to the reaction of nitrite with secondary amines and amino acids in muscle proteins as well as in the gastrointestinal tract.
The use of Staphylococcus strains for color formation is based on their ability to reduce inorganic nitrate to nitrite which is further degraded into the above described nitric oxide (NO), the active compound in the color formation process. The nitrate could be provided directly as nitrate salt or indirectly with a natural nitrate source (vegetable powders). Even if a nitrite salt is added, the addition of Staphylococcus strains is recommended as nitrite is partially re-converted to nitrate.
Staphylococcus carnosus and less frequently Staphylococcus xylosus are standard Staphylococcus strains used for the purpose of nitrate reduction and color formation. These strains are properly working at higher fermentation temperatures but are less active at low temperatures, below 6° C. As low production temperatures are preferred by the industry due to hygiene reasons a Staphylococcus strain having nitrate reductase activity at low temperatures is wanted.
Staphylococcus vitulinus is a strain known to have nitrate reductase activity at low temperatures and it has been used in combination with lactic acid bacteria for reddening of meat (WO2010/067148).
However, there is a need for methods which improve the nitrate reduction and color formation in food products and as a result may lead to a decrease in the production time necessary for the desired reddening of the food products and thereby lead to reduction in cost of production of such products.